MIAMI — Mitt Romney is striding into the homestretch of the pivotal GOP Florida presidential primary with the confidence of a resurgent front-runner.

His main rival, Newt Gingrich, is hustling around the state as he tries to rekindle the energy that lifted him to victory in the South Carolina primary. He says he could lose Tuesday in Florida but promises to soldier on.

Gingrich picked up the endorsement Saturday of Herman Cain, a Georgia businessman, tea party favorite and former presidential hopeful. Cain's bid for the White House was derailed by allegations he sexually harassed several women.

Rick Santorum cancelled his Sunday campaign events after his young daughter was hospitalized. She suffers from a serious genetic disorder.